Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import *
H,W = map(int,input().split())
S = [input() for h in range(H)]
V = [W*[0] for h in range(H)]
V[0][0] = 1
Q = deque([(0,0)])
while Q:
  x,y = Q.popleft()
  for dx,dy in ((-1,0),(0,-1),(1,0),(0,1)):
    if 0<=x+dx<H and 0<=y+dy<W and V[x+dx][y+dy]==0 and S[x+dx][y+dy]==".":
      V[x+dx][y+dy] = V[x][y]+1
      Q.append((x+dx,y+dy))

if V[H-1][W-1]==0:
  print(-1)
else:
  print(H*W-sum(s.count("#") for s in S)-V[H-1][W-1])